worried about your mock exam result?

After your Year 12 mock exam results have been given back you may be quite concerned about the grade you received. There are a number of things you can do about this, the first of which will no doubt be to do the appropriate amount of revision over the holidays. You will also benefit from more past paper practise. The problem is that since the syllabus changed this year we have no actual past papers for you to attempt.

However, the old syllabus has many very similar questions which cover mostly the same content and you can download them, along with the answer schemes, here.

AQA unit 1 past papers

You will recognise many of the 2006 and 2007 questions from the yellow homework booklet you have been using, but beware as some content has now been deleted or has moved to the module you will study after christmas, eg. chemistry of group 2 metals. As a general rule, if you've not been taught it, you don't need to know it.

module 4 past paper answers

If you are looking for answers for the orange module 4 booklet you can download them from here, as they are no longer on the AQA website.

Jan 2002

June 2002

Jan 2003

June 2003

the periodic table of videos

I've put an exciting new resource into the Useful Links section down the right hand side of the blog, and also put a link from this post.

Periodic Table of Videos

It's set of short videos, one for each of the elements in the Periodic Table, produced at Nottingham University and featuring some impressive Chemistry.

Keep an eye out for the Professor with the mad grey hair.

year 12 help with formulae and equations

Some of you have been struggling to get to grips with formulae and equations so follow the link below for a downloadable worksheet which will hopefully help to sort out some of your problems.

common ions, formulae and equations

large hadron collider

The biggest, most expensive experiment in history begins this week and is attracting both scientific hyperbole and hysteria. Some say it will reveal the universe's secrets and lead to the elusive Theory of Everything. A few fear that unleashing unimaginable power beneath the Swiss countryside will result in the end of the world. On Wednesday scientists will find out whether the LHC’s £3 billion cost has paid off.

The first beams of particles have already been successfully fired around nearly half of the 17-mile tunnel in Switzerland, where Cern (the European Organisation for Nuclear Research) is based, as part of preliminary testing. If Wednesday’s start-up goes smoothly a second beam will be fired into the machine travelling in the opposite direction, with the two forced to collide. The products of those collisions could give physicists their best insight yet into the structure and origins of the universe.

The Big Bang is what they are trying to recreate. Or rather what happened a trillionth of a second after the universe was created by an explosion, 13.7 billion years ago. For that tiny moment, it is believed everything was molten plasma. This cooled to create everything we see around us. The hope is that by recreating that moment, in miniature, the scientists will be able to see things that are invisible now. Why though?

Well, the problem is that we don't have any real evidence for our theory of why things have mass. In 1964 Professor Peter Higgs of Edinburgh University predicted an unseen particle that provided mass, the Higgs boson. The hope is it will be detected for the first time and its detection may give us a Theory of Everything, the Holy Grail of science. This is a unifying theory providing one explanation for the forces at work in the natural world, from the nucleus of an atom to the movements of the planets. Sounds like alchemy to non-scientists, but some very respectable minds believe it is possible, and that the collider may show the way.

Some scientists, on the other hand, went to the European Court for Human Rights to try to stop the collider being turned on. They fear it may create a black hole, which would certainly violate our rights by sucking the planet into... well we don't really know, but it's probably not good news. Professor Sir Chris Llewellyn Smith of Cern says: "The chance we produce a black hole is minuscule." Which is not all that reassuring. Or as Professor Brian Cox puts it, "anyone who thinks that the LHC is dangerous is a t--- ".

However, is it not entirely possible that a few seconds before the original big bang there may have been a group of eminent scientists stood around in an alternate universe waiting patiently for someone flick a switch and turn a very large particle collider on? In any case, they will only send the protons in one direction this week. The collisions start in October. Until then, at least, we're safe.

large hadron collider guide

official LHC website

scientifically correct LHC rap
I know physicists are excited about it, but a rap?

liquid nitrogen bomb

Liqiud nitrogen boils at a temperature of −196 °C and since the liquid to gas expansion ratio is 1:694 it will very quickly build up enough pressure to make it quite unsafe to seal into an empty plastic bottle.

hydrogen pringles

A pringles tub with a small hole in the top, filled with hydrogen gas and ignited, will burn away quietly until the hydrogen/air mix is just right. Then a small explosion is observed. The second attempt has the mix just right to begin with upon ignition.

august kekulé

Friedrich August Kekule von Stradonitz (also August Kekulé) (1829 – 1896) was a German organic chemist. One of the most prominent chemists in Europe from the 1850s until his death, especially in the theoretical realm, he was the principal founder of the theory of chemical structure.

The theory of chemical structure (1857-1858) was a descripton of the ability of carbon atoms to link to each other tetravalently. The idea of the self-linking of carbon atoms provided the first formulae where lines symbolise bonds connecting the atoms. For organic chemists the use of structural formulae to explain the formation of molecules provided dramatic new clarity of understanding, and as a consequence the field of organic chemistry developed explosively from this point.

However, Kekulé's most famous work was based on the structure of benzene. Early suggestions at the time had been based on a linear chain of 6 carbon atom with 4 double bonds. The empirical formula for benzene had been long known, but its highly unsaturated structure was challenging to determine. The study of aromatic compounds was in its earliest years, and too little evidence was then available to help chemists decide on any particular structure. In 1865 Kekulé published a paper in French suggesting that the structure contained a six-membered ring of carbon atoms with alternating single and double bonds. The next year he published a much longer paper in German (his native language) on the same subject.

When Kekulé spoke of the creation of the theory, he said that he had discovered the ring shape of the benzene molecule after having a day-dream of a snake (dirty boy! Freud would have a field day) seizing its own tail. This vision, he said, came to him after years of studying the nature of carbon-carbon bonds.

Although it was an exciting and well thought out idea at the time, further evidence soon came to light that demonstrated that Kekulé was perhaps mistaken in his proposed structure of benzene. You will need to be able to describe and explain this evidence for your module 4 exam.

The evidence includes:

a) problem with bond lengths
b) lack of reaction with bromine (benzene will not undergo electophilic addition)
c) problem with enthalpy of hydrogenation data

Check your notes to make sure you can explain each piece of evidence.

module 4 kinetics

Some of you have had problems drawing gradients on curves in order to deduce the rate of reaction on concentration/time graphs. The powerpoint below will allow you to check this skill and compare it to the graphs that you produced on your recent homework.

gradients from graphs

This next download is a set of interactive kinetics questions of a similar type to the ones you will find on your module 4 exam. Answers are provided.

kinetics exam questions

thomas midgley

Thomas Midgley, Jr, was an American Engineer and latterly a Chemist whose contribution to science was almost impossibly unfortunate and regrettable, since he was responsible for possibly two of the most destructive inventions of the 20th century.

Midgley used a knowledge of chemistry and, in particular, the Periodic Table to make two significant developments – lead based anti-knock additives for internal combustion engines and chlorofluorocarbons (CFCs) as the working fluids in refrigerators. Both these developments were of enormous commercial importance at the time (the 1920s) and remained in use for over half a century.

His anti-knocking additive, tetraethyl lead, was used in petrol until it began to be phased out in the 1970s and was totally withdrawn in the UK in 2000. Lead and its compounds are neurotoxins, and studies suggested that the lead(IV) oxide given out by vehicles using leaded fuel was causing brain damage in children growing up in areas close to major roads. Lead also poisons the catalysts of cars using catalytic converters used to convert carbon monoxide, nitrogen oxides and unburned hydrocarbons in car exhausts into innocuous carbon dioxide, nitrogen and water. In fact, the dangers asociated with lead and its derivatives were well known at the time, and probably the reason that the corporations involved with the production of tetraethyl lead chose to call their new petrol additive simply 'ethyl'. Much more consumer friendly.

Not content with putting enough lead into the atmosphere to kill people for decades, he turned his hand to another problem. In the 1920's compounds such as propane, ammonia, sulfur dioxide and chloromethane were used as refrigerant gases. All had disadvantages such as toxicity, flammability or chemical reactivity. One refrigerator leak in a hospital in Cleveland in 1929 killed over 100 people. What was required was a non-toxic, non-flammable, chemically inert gas/volatile liquid. In 1928, Midgley was called in to help with the search and with an instict for the regrettable that was almost uncanny, Thomas Midgley invented chloroflourocarbons, CFC's.

With a degree of showmanship, Midgley even demonstrated the suitable properties of his new discovery at a meeting of the American Chemical Society by inhaling some of the gas and then exhaling onto a lighted candle, which was extinguished.

CFCs went on to be an important commercial success, being used for several decades as refrigerator fluids and deoderant propellants. We now know that the chemical inertness of the CFCs (due in part to their strong C-F bonds) held the seed of a major environmental problem. On release into the atmosphere, CFCs do not break down and a large ‘reservoir’ of them built up in the atmosphere. However, high in the atmosphere they do decompose under the action of ultraviolet light, leading to the formation of chlorine radicals which catalyse the breakdown of ozone to oxygen. Since ozone absorbs ultraviolet radiation from the Sun, this leads to a greater intensity of UV radiation at the Earth’s surface causing problems such as increased rates of skin cancer, cataracts in the eyes, the death of plankton and faster decomposition of rubber, plastics and dyes. This began to be understood in the 1970s and CFCs have been withdrawn since the Montreal Protocol of 1987.

Although is easy to deride Midgley as being responsible for two major environmental catastrophes this is, of course, with hindsight. At the time both tetraethyl lead and CFCs were major scientific and economic breakthroughs and their consequences a half a century later simply could not have been predicted by Midgley or anyone else.

Finally, there is the bizarre tale of Midgley’s tragic end. In 1944, at the age of 51, Midgley contracted polio and lost the use of his legs. Using his engineering skills he devised a pulley system to enable him to get out of bed, which worked well until one day he became entangled in the ropes and was strangled.

jelly baby

Basic fire triangle requirements, essential for all combustion, are heat, oxygen and fuel. Here the heat has already been provided by a bunsen, the oxygen mainly comes from the molten compound in the boiling tube, potassium chlorate, KClO₃, and the fuel? Well that's the sugar in the poor old jelly baby.

magnesium and copper oxide

The two metals magnesium and copper are poles apart in terms of reactivity, as anyone with a passing knowledge of the reactivity series of metals will be aware.

This can be violently demonstrated by the reaction between magnesium powder and copper oxide in a small porcelain crucible. It takes a while to get hot enough, and then a rather spectacular displacement reaction occurs.

module 2 and 3 past paper answers

If you're not already maxed out on past papers, here you can find access to papers from 2005 and 2006 that you will not have seen before. You can download both the paper and the mark scheme seperately.

AQA past papers

Also, if you are still thirsty for more I have the answers to the homework booklets we have used sporadically throughout the last few months. However, beware that some questions contain content that has now been removed from the syllabus (eg. any reference to thiosulphate titration calculations for CHM2 and the mechanism for the dehydration of alcohols to alkenes for CHM3). The content changed slightly when the papers moved from 90 mins to 60 mins in length. If unsure, ask.

AS2 answers (green booklet)

AS3 answers (blue booklet)

Best of luck with the forthcoming exams, and don't forget that you can always come in for help while you are off on study leave.

albert hofmann

Last Wednesday, 30th April, Albert Hofmann, the Swiss chemist who discovered the hallucinogenic drug LSD, died of a heart attack at his home in Basel at the age of 102.

Mr Hofmann first produced LSD in 1938 while researching the medicinal uses of plants, in particular a type of crop fungus. While working with the drug in the Sandoz pharmaceutical laboratory a few years after first producing it, Mr Hofmann accidentally ingested some of the drug through his fingertips.He went home and experienced what he described as visions of "fantastic pictures, extraordinary shapes with intense, kaleidoscopic play of colours".

Hofmann argued for decades that LSD could help treat mental illness and over 2000 research papers were published on the drug, offering hope for sufferers of a range of conditions from drug and alcohol addiction to psychiatric illnesses of various kinds. However, in the 1960s it became a popular street drug and was soon made illegal, much to Hofmann's regret, and he was forced to concede that LSD could be very dangerous in the wrong hands.

Albert Hofmann obituary

transition metal reactions

Year 13 powerpoint stuff for transition metals. It's pretty good but I'll let you decide if it's better than my technicolour sheet (how can it be?)

reactions of transition metals

year 12 rates answers

When you have managed to have a go at the worksheet on the earlier post have a look at the answers here.

rate of reaction answers

Remember to also make sure you are happy with the Maxwell-Boltzmann distribution. Exam questions, particularly the longer type section B variety, commonly focus on this.

year 13 work for paternity leave

Crikey. I'll be glad of a rest on Friday when I'm back in. Anyway, we've nearly finished the first chunk of transition metal chemistry. We've covered transition metal complexes and their uses, catalysis and the variable oxidation state of these metals.

We also need to know about transition metals and colour so you will need to read through pages 219-222 of your A2 text book and make notes on 'the origin of colour' and 'using colour to determine concentration'. We will be doing some practical work to reinforce these ideas on Friday and during the following week.

Also, you will need to ensure that your homework (the 5 past paper sheets I gave you last week) is up to date for Friday.

Finally, seeing as we are coming to the end of a big dollop of transition metal stuff it would make sense to have a small test before Easter, so you might want to make sure you understand everything we've done so far. Use the questions on pages 240 and 241 to check your level of understanding (answers are in the back of the book).

year 12 work for paternity leave

Right then. I'll be back in on Friday, but to keep you going you need to read up about kinetics (rates of reaction) on pages 106-109 of your AS text book. If you didn't get one you'd better sort yourself out with one from the prep room in Science (£20 deposit that you can get back when you return it).

Most of the kinetics stuff eg. collision theory, is very similar to your GCSE work. The only significant new content is the Maxwell-Boltzmann distribution of molecular energies (look it up and make sure you can draw, label and explain the graphs appropriately for different temperatures).

Obviously this is only a short topic for module 2, and should be quite straightforward for you to get to grips with yourself. Make sure you try these questions on the downloadable worksheet below.

rate of reaction

You will need to get some graph paper to complete this. I'll post some answers later in the week.

Also have a look at this to help your understanding of the Maxwell-Boltzmann distribution.

Maxwell-Boltzmann

Finally, try some of the questions on pages 110-111 of the text book to check your understanding (answers are in the back).

a level work

As you may probably know, I will not be in for a few days this week due to the birth of my son Alfie.

Lessons will return to normal on Friday this week.

I will post your work here later on today when I have a bit more time. Please check back this evening and ensure that you endeavour to get up to date by Friday or our next lesson.

Thanks, Mr Smith

hindenburg disaster

LZ 129 Hindenburg was a German zeppelin or airship, and at the time it was the largest aircraft ever built. During its second year of service, it went up in flames and was destroyed while landing at Lakehurst Naval Air Station in New Jersey, U.S., on 6 May 1937, having left Frankfurt, Germany 3 days earlier. Thirty-six people were killed, although surprisingly given the nature of the accident, the majority of the passengers survived. Several theories exist as to the cause of the accident, the most likely of which is a build up of static electriciy on the outside of the airship canopy causing a spark which ignited the hydrogen within.

Modern airships are of course filled with helium, lighter than air but also inert or unreactive. Much safer for all concerned. Except that this could have been used anyway in the 1930's in place of hydrogen. The Americans were already doing so, having discovered large amounts of helium over 30 years previously during drilling operations, and far from being a rare element helium was found to be present in vast quantities under the American Great Plains.

This put the United States in an excellent position to become the world's leading supplier of helium and they began to develop military uses for the gas, including airship use, and set up the National Helium Reserve in 1925 at Amarillo, Texas with the goal of supplying military airships in time of war and commercial airships in peacetime.

However, due to a US military embargo against Germany that restricted helium supplies, the Hindenburg was forced to use hydrogen as the lift gas. Still, without the Hindenburg disaster we might have been deprived of one of the most iconic rock album covers of all time.

bunhead

KS3 pupils from Turton visited the Catalyst Centre in Widnes today where they bore witness to Dr Bunhead's Exploding Energy Show. The show proved to be a big hit with the students and with Mr Smith, who came face to face with his doppleganger and personal hero. Mr Smith (above centre) and Dr Bunhead (above left) agreed that they were both quite good at blowing things up. Watch out with that potato bazooka.

For more Bunhead related antics check out Dr Bunhead's Website

oil strike

Just last month (January 2008) the Anglo-Dutch oil firm Shell reported annual profits of $27.56 bn (£13.9 bn), a record for a UK-listed company. Much of the rise in profits was attributed to rising oil prices, which have nearly doubled since last year. However, the level of profit announced has been described as "quite frankly obscene" and clearly doesn't sit well with many drivers who are paying a premium to fill their cars at petrol pumps around the country.

The oil company itself went to great lengths to stress that little of their profit came from petrol forecourts, with the majority of the price paid at the pump already going straight to the government. Very reassuring.

So, if you think you can make more money than Shell, have a go at the game below where you have been drafted in as the managing director of your own oil exploration company. You will have to answer questions on oil and fractional distillation to ensure the smooth running of the company.

play oil strike

born haber cycles

Ahh, the boundless joy of Born Haber cycles. If they're sending you round in circles then try these resources.

Download a powerpoint to help your understanding
NaCl Born Haber

Build your own cycle with this exercise
NaCl drag and drop

organic mechanisms

All the organic mechanisms you need for CHM3 (now CHEM2) and CHM4 (CHEM4). The link below will take you to a file sharing site where you can either view or download the presentation.

organic mechanisms